initial commit

snep.cpp

@@ -0,0 +1,122 @@
+
+#include "snep.h"
+#include "PN532_debug.h"
+
+int8_t SNEP::write(const uint8_t *buf, uint8_t len, uint16_t timeout)
+{
+	if (0 >= llcp.activate(timeout)) {
+		DMSG("failed to activate PN532 as a target\n");
+		return -1;
+	}
+
+	if (0 >= llcp.connect(timeout)) {
+		DMSG("failed to set up a connection\n");
+		return -2;
+	}
+
+	// response a success SNEP message
+	headerBuf[0] = SNEP_DEFAULT_VERSION;
+	headerBuf[1] = SNEP_REQUEST_PUT;
+	headerBuf[2] = 0;
+	headerBuf[3] = 0;
+	headerBuf[4] = 0;
+	headerBuf[5] = len;
+	if (0 >= llcp.write(headerBuf, 6, buf, len)) {
+		return -3;
+	}
+
+	uint8_t rbuf[16];
+	if (6 > llcp.read(rbuf, sizeof(rbuf))) {
+		return -4;
+	}
+
+	// check SNEP version
+	if (SNEP_DEFAULT_VERSION != rbuf[0]) {
+		DMSG(F("The received SNEP message's major version is different, me: "));
+		DMSG(SNEP_DEFAULT_VERSION);
+		DMSG(", their: ");
+		DMSG(rbuf[0]);
+		DMSG("\n");
+		// To-do: send Unsupported Version response
+		return -4;
+	}
+
+	// expect a put request
+	if (SNEP_RESPONSE_SUCCESS != rbuf[1]) {
+		DMSG("Expect a success response\n");
+		return -4;
+	}
+
+	llcp.disconnect(timeout);
+
+	return 1;
+}
+
+int16_t SNEP::read(uint8_t *buf, uint8_t len, uint16_t timeout)
+{
+	if (0 >= llcp.activate(timeout)) {
+		DMSG("failed to activate PN532 as a target\n");
+		return -1;
+	}
+
+	if (0 >= llcp.waitForConnection(timeout)) {
+		DMSG("failed to set up a connection\n");
+		return -2;
+	}
+
+	uint16_t status = llcp.read(buf, len);
+	if (6 > status) {
+		return -3;
+	}
+
+	// check SNEP version
+	
+	// in case of platform specific bug, shift SNEP message for 4 bytes.
+	// tested on Nexus 5, Android 5.1
+	if (SNEP_DEFAULT_VERSION != buf[0] && SNEP_DEFAULT_VERSION == buf[4]) {
+		for (uint8_t i = 0; i < len - 4; i++) {
+			buf[i] = buf[i + 4];
+		}
+	}
+	
+	if (SNEP_DEFAULT_VERSION != buf[0]) {
+		DMSG(F("SNEP->read: The received SNEP message's major version is different, me: "));
+		DMSG(SNEP_DEFAULT_VERSION);
+		DMSG(", their: ");
+		DMSG(buf[0]);
+		DMSG("\n");
+		// To-do: send Unsupported Version response
+		return -4;
+	}
+
+	// expect a put request
+	if (SNEP_REQUEST_PUT != buf[1]) {
+		DMSG("Expect a put request\n");
+		return -4;
+	}
+
+	// check message's length
+	uint32_t length = (buf[2] << 24) + (buf[3] << 16) + (buf[4] << 8) + buf[5];
+	// length should not be more than 244 (header + body < 255, header = 6 + 3 + 2)
+	if (length > (status - 6)) {
+		DMSG("The SNEP message is too large: "); 
+		DMSG_INT(length);
+		DMSG_INT(status - 6);
+		DMSG("\n");
+		return -4;
+	}
+	for (uint8_t i = 0; i < length; i++) {
+		buf[i] = buf[i + 6];
+	}
+
+	// response a success SNEP message
+	headerBuf[0] = SNEP_DEFAULT_VERSION;
+	headerBuf[1] = SNEP_RESPONSE_SUCCESS;
+	headerBuf[2] = 0;
+	headerBuf[3] = 0;
+	headerBuf[4] = 0;
+	headerBuf[5] = 0;
+	llcp.write(headerBuf, 6);
+
+	return length;
+}